Thermal Stabilization Graph

[Endo]

I haven't seen many posts in the last week so I thought I'd post this. Perhaps it has been done before, perhaps not.

From my Scace sessions I had a good idea the warmup time was somewhere around 45 minutes. Still I was wondering how much I could push this so, I did a little experiment:

Starting from 25C, the brew boiler took 3 min 46 sec to get up to 94C, and then I recorded every time the heater LED started flashing and plotted the time between "heater ons" versus time since power on. I figured when the time between "heater ons" became constant, that would be when all metal had achieved steady state. As you can see from the graph, this happens around 40 to 45 minutes. I could probably push this up to 30 minutes without a huge effect.

I did it with my Mini Vivaldi and a bottomless PF and only ran the brew boiler. I might try it again with a regular double PF (which has more thermal mass).

I'd also be very interested to see how other machines (like some big boiler HXs) compare.

Thermal Stabilization Graph

tsg.jpg (39.51 KiB) Viewed 16813 times

[txrpls]

Slow weekend?

[Endo]

Slow weekend?

Quite busy actually. I just thought I'd do something constructive while watching my Behmor do a 40 min roast and cool down.

Like I always say, I learned a lot from this forum, just trying to give back a bit.

[slo]

And thank you for taking the time to do such a thing! I found it very interesting.

One detail here, the time would be reduced with the Steam boiler active at the same time (if on the 20 AMP setting) because of heat transfer inside the machine. Another thing that will influence the result is insulation, external temperature.

I do not think that a comparison with a HX machine is relevant on this. Apple and turnip!

[Endo]

One detail here, the time would be reduced with the Steam boiler active at the same time (if on the 20 AMP setting) because of heat transfer inside the machine. Another thing that will influence the result is insulation, external temperature.

I do not think that a comparison with a HX machine is relevant on this. Apple and turnip!

On 20 amp, the steam boiler would definitely help increase the internal temperature. Adding cups and towels on top as well I suppose. But, I don't think it would have more than a 1 minute impact. Still, it's worth trying to see.

I don't think insulation would change things much. I haven't heard of anyone insulating the brew boiler.

External temperature was 25C in my test. I higher temp would definitely give it a head start.

The double PF would have some effect. Scale buildup too? All things worth trying, but again, I suspect all these things combined would only change things by a minute at most.

Now a 1.5L HX! That would be interesting. Maybe somebody will post a graph. I expect anyone owning a HX will simply take the line "I always leave mine on".

[JohnB]

Slow weekend?

Quite busy actually. I just thought I'd do something constructive while watching my Behmor do a 40 min roast and cool down.

Like I always say, I learned a lot from this forum, just trying to give back a bit.

A 40 minute roasting cycle?? Chicken??

[Endo]

19 minute roast and equivalent cooldown period. I wish I could dump the beans without waiting for the cooldown.....but after watching the movie "Backflash", I've decided to err on the safe side and just wait.

I'm roasting a new recipe I saw online:

1/3 Brazilian Santos
1/3 Tanzaniain Peaberry
1/3 Papa New Guinea

Pretty tasty!

[JohnB]

How many minutes before the beans reach room temp on that uber extended cool down cycle. Takes 3 minutes with my set up. 19 minutes is a loooong roast time. When do you hit 1C? How long of a stretch?

[Endo]

How many minutes before the beans reach room temp on that uber extended cool down cycle. Takes 3 minutes with my set up. 19 minutes is a loooong roast time. When do you hit 1C? How long of a stretch?

I'm roasting 13.5 oz on P1 profile. I get 1C at 16:30 and 2C at 18:45 (that's when I hit cool). I think the cool period is actually closer to 12 min (can't remember exactly). The Behmor runs an afterburner during the cooling to get rid of the smoke. It's seems very effective at this. I've tried opening the door after about 1 min into cooldown, but I figure it's an increased fire risk (and it's messy with flying chaff), so I now avoid it. Personally, I don't see a big problem with the extend cooldown.

Overall I'm very happy with the Behmor. It's cheap price and large batch size really seperate it from the others.

[JohnB]

Overall I'm very happy with the Behmor. It's cheap price and large batch size really seperate it from the others.

That & the fact that its unGodly slow!

[caf4brains]

I regularly open the door to the Behmor when I'm roasting outside to speed up the cooldown. Chaff blows around more but I've never had any inflammitory moments.

[Endo]

I regularly open the door to the Behmor when I'm roasting outside to speed up the cooldown. Chaff blows around more but I've never had any inflammitory moments.

Good to know. Then again, if you're outside, the consequences of a fire are much less.

I think it depends on certain factors; like whether the beans are particularly chaffy, you are roasting a large batch (above 14 oz) or if you are roasting very far beyond 2C. All these factors increase the chance of fire. So if you try pusing these limits, sometimes opening the door can add enough oxygen to turn a small bit of smoldering chaff into a raging inferno.

If you stay below these limits, I believe you can safely open the door after the heaters stop glowing red (about 1 min into cooldown).

[chas]

I never knew you could get coffee beans to burn like charcoal until I owned a Behmor.